Method for lining rotary kilns

ABSTRACT

A method for lining rotary kilns with monolithic castable refractory comprising placing rings made of segments preferable adjustable attached to each other so the rings can be adjusted to the desired circumference, the rings having removable spacer elements which support the rings on and space them from the kiln shell. Forms are attached to the rings and castable refractory place between the forms and the kiln shell to form the lining. The lining is cast in sections, the kiln being rotated so that the casting of each section is done in a downward direction. The spacer elements are removed from each section prior to casting refractory material in that section.

Sept. 17, 1974 L, Mm 3,836,612

METHOD FOR LINING ROTARY KILNS Original Filed Feb 18, 1971 2 Sheets-Shet 1 J5 4 FIE-j- Sept. 17, 1974 L. L. MANN METHOD FOR LINING ROTARY KILNS 2 Sheets-Sheet 2 Original Filed Feb 18, 1971 United States Patent 3,836,612 METHOD FOR LINING ROTARY KILNS Larry L. Mann, Mexico, Mo., assignor to Kaiser Aluminum & Chemical Corporation, Oakland, Calif. Original application Feb. 18, 1971, Ser. No. 116,484, now Patent No. 3,733,045, dated May 15, 1973. Divided and this application Jan. 11, 1973, Ser. No. 322,894

Int. Cl. F27d 1/16 U.S. Cl. 264-30 5 Claims ABSTRACT OF THE DISCLOSURE A method for lining rotary kilns with monolithic castable refractory comprizing placing rings made of segments preferably adjustably attached to each other so the rings can be adjusted to the desired circumference, the rings having removable spacer elements which sup port the rings on and space them from the kiln shell. Forms are attached to the rings and castable refractory placed between the forms and the kiln shell to form the lining. The lining is cast in sections, the kiln being rotated so that the casting of each section is done in a downward direction. The spacer elements are removed from each section prior to casting refractory material in that section.

CROSS-REFERENCE TO RELATED APPLICATION This application is a division of application Ser. No. 116,484, filed Feb. 18, 1971, now U.S. Pat. No. 3,733,045, issued May 15, 1973.

BACKGROUND This invention concerns the lining of rotary kilns and particularly a method and apparatus for installing a monolithic lining of castable refractory material.

It has been customary for many years to line rotary kilns with bricks which are individually set in place to form the lining. However, in recent years the advantages of casting a continuous, monolithic section in a rotary kiln have been recognized, and castable refractory materials have been developed for this application.

In order to form a castable refractory monolithic lining in a rotary kiln, it is necessary to provide a temporary form for holding the castable refractory in place until it sets. Such forms can be made of boards, plywood, sheet metal, or any other suitable material. It will also be apparent that such forms must be supported in place by bracing which will not only carry the weight of the forms, but will also resist the hydrostatic pressure of freshly poured refractory.

In the past, such supports have generally been internal bracing within the central portion of the rotary kiln. However, such internal bracing has Obvious drawbacks, for example it impedes movement of men and materials into and out of the kiln during lining.

A more recent development has been to tie the forms to the kiln shell by means of snap ties which are welded at one end to the kiln shell, the other end passing through the form and fastening the latter in place, as is set forth more fully in U.S. Pat. 3,445,099. However, the use of snap ties has the disadvantage that carefully aligned holes must be drilled in the forms to receive the ties. Also, the ties remain in place after the refractory castable has set, providing a continuous metal path from the interior of the kiln through the lining to the metal shell. It is felt by some that these snap ties in 'the cast lining may constitute weak spots at which the lining may be more rapidly attacked and worn away, and also that they may provide paths along which heat may leak from the kiln.

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SUMMARY 'OF THE INVENTION It has now been discovered, according to this invention, that the foregoing disadvantages of prior art methods of casting monolithic linings in rotary kilns can be overcome by an apparatus comprising a plurality of segmented ring structures, the rings preferably being made up of adjustably attached arcuate segments, and being supported concentrically within the rotary kiln shell by at least three support or spacer elements removably attached to the ring at circumferentia-lly spaced intervals. Preferably, there is one spacer element for each segment in a ring. In casting a monolithic lining using such apparatus, a starter board is placed between the kiln shell and the rings, and forms attached to the outer surfaces of the rings circumferentially from the starter board for a portion of the distance around the rings. This section is filled with castable refractory, and then a further section of forms applied to the rings. As the placing of forms and casting of refractory proceeds about the kiln circumference, whenever necessary the spacer elements are removed before applying forms to the portion of the rings where they were located, and the kiln itself is rotated so that the refractory is always cast in a downward direction into the space between the forms and the kiln shell.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a transverse cross-sectional view of a rotary kiln showing the apparatus of the present invention in place;

FIG. '2 is a longitudinal sectional view of a rotary kiln taken along the line 22 of FIG. 1;

FIG. 3 is a diagram of a rotary kiln showing its division, for purposes of description, into four quadrants;

FIG. 4 is an enlarged view of the portion of FIG. 2 surrounded by line 44; and

FIG. 5 is an enlarged view, partially in section, of the portion of FIG. 1 surrounded by line 5-5.

DETAILED DESCRIPTION Rings 10 are preferably made up of 'arcuate segments 11 adjustably attached to each other. For example, attachment by means of joining elements 12 which are attached by rivets 13 to one end of a segment 11 and by bolts 14, passing through an elongated slot 16 in join ing element 12, to the opposite end of the next adjacent segment 11.

In preparing to line a rotary kiln, two or more rings 10 will be assembled outside the kiln, rings 10 being assembled to have a diameter which, taking into account the thickness of forms 21 to be attached to rings 10, will provide a space between forms 21 and kiln shell 23 equal to the thickness of refractory lining desired. It will be apparent that when rings 10 are made up of segments 11 adjustably attached to each other, it is very easy to achieve, within limits, any desired circumference in rings 10. In a preferred embodiment, when rings 10 are made up of a given number of segments 11, for example the eight segments shown in the drawings, then the degree of adjustment between segments 11 will be such that the circumference of ring 10 with segments 11 adjusted to their maximum separation is at least as large as the circumference obtainable with one greater num ber of segments in the ring (i.e., nine for the embodiment illustrated) when segments 11 are adjusted to their closest position, and therefore minimum circumference. With this preferred embodiment, it will be possible to construct rings 10 of any circumference above a certain minimum. The advantages of such a structure in lining kilns of different sizes will be apparent.

Segments 11 may be formed, as shown, of U-shaped channel stock, with the legs of the U forming the outer surfaces of rings so as to provide space for the heads of rivets 13 and bolts 14, as well as for nuts 28 (described below).

After the requisite number of rings 10, at least two, have been assembled, they are placed concentrically within kiln shell 23 in the area to be lined, being supported by detachable spacer elements such as spacer bolts 17. These are ordinary bolts of the requisite length, which however need be threaded only along the portion of their shank which passes through segment 11. It will be understood that segments 11 are threaded to receive spacer bolts 17, for example by means of nuts 28 welded within the U-channel forming segment 11. For convenience of adjustment, bolts 17 may have handles 31 attached to their heads.

The number of rings 10 used in lining a given section of kiln will depend on the longitudinal length of the section. It has been found that good results are obtained when rings 10 are spaced no more than four feet apart along the length of the kiln. It will also be understood that, while the method and apparatus of the present invention will most often be used to install a repair or replacement section of kiln lining, the method is also applicable to installation of a new lining.

After rings 10 are in position within the kiln, a starter board 18, extending from kiln shell 23 to the outer surface of rings 10 and longitudinally the length of the section to be lined, is set in place. It will be understood that, both for convenience in placing starter board 18 and for subsequent casting of the lining, it will be most convenient to place spacer bolts 17 in each of rings 10 in a straight line along the length of the kiln, the so aligned spacer bolts 17 forming a set of spacer bolts. It will also be understood that it will be most convenient to place starter board 18 immediately adjacent a set of such spacer bolts such as the set 17' shown.

Starter board 18 will be placed in one of the lower quadrants of the kiln. As illlustrated in FIG. 3, for purposes of discussion it is possible to divide the cross section of a rotary kiln by vertical and horizontal diameters into four quadrants, these being labeled a, b, c, and d, in FIG. 3. The two lower quadrants are c and d. As will be apparent from the subsequent discussion, whether starter board 18 is placed within quadrant c or quadrant d will depend on the direction in which the kiln is rotated. When the kiln is rotated counterclockwise, looking in the direction of FIG. 1, starter board 18 will be placed the quadrant c, as shown. For clockwise rotation, it will be placed in quadrant d.

Although starter board 18 is placed adjacent the set of spacer bolts 17', it will generally be found preferable to support it in position, as by brace 19.

On the inner side of starter board 18 is placed tongue 24, which will form a longitudinal groove in the starting face of the cast lining. This groove will be filled with refractory castable during the pouring of the last section of lining and form a mechanical interlock between the material which is cast first and that which is cast last.

After starter board 18 is in position, forms 21 are placed along the outer surfaces of rings 10, extending from starter board 18 circumferentially to the vicinity of the next circumferentially adjacent set of spaced bolts 17" and longitudinally over the entire section of lining to be cast. As shown in FIG. 2, forms 21 will preferably overlap adjacent sections of refractory 22 in casting a replacement section of the kiln. Where this method is used to install a new lining in a previously unlined kiln, circumferential end forms (not shown) must be installed to replace the refractory 22 already in place in the embodiment illustrated. Although boards are shown as making up forms 21 in the drawings, it will be understood that other equivalent material, for example corrugated sheet metal, can be used to construct forms 21. Forms 21 may 4 be attached to rings 10, for example by means of tie wires 27.

If necessary to achieve exact positioning of forms 21, wedges (not shown) can be driven between forms 21 and rings 10 to secure tight and exact positioning.

After the first section of forms 21 is in place, castable refractory 26, any of many readily available commercial products, is poured into the space formed by starter board 18, forms 21 and kiln shell 23. As is customary, vibration can be applied to the freshly cast refractory to secure maximum density. If desired, metal anchors 29 may be welded to kiln shell 23 and embedded in refractory castable 26, as is well known in the art.

After the first section of lining has been cast, the set of spacer bolts 17" is removed, and further forms 21 attached to the outer surfaces of rings 10, extendin circumferentially from previously placed forms 21 to adjacent the next circurnferentially spaced set of spacer bolts 17" and longitudinally over the entire area to be cast.

After the second section of forms 21 has been installed, and the previously cast section of refractory has taken an initial set, the entire kiln is turned, counterclockwise for the kiln shown in the drawings, so as to place the section of forms 21 which is now ready to receive castable refractory into lower quadrant c. It will be appreciated that, by this method, refractory will always be poured in a downward direction, resulting in greater ease of operation and also better placement.

This process of removing sets of spacer bolts 17, placing further forms 21, rotating the kiln, and placing more refractory castable 26, is continued until the last set of spacer bolts 17 is removed. Starter board 18 and brace 19 are then removed. For ease in removing starter board 18, it will often be found convenient to make it in two or more sections. Next, the kiln is rotated so that the section of lining remaining to be cast is placed at the circumferentially lowest part of the kiln. This section is then filled with refractory castable 26. In casting this final section, the use of forms 21 is not necessary, but if, for example, corrugated metal has been used for forms 21, it may be desirable to place a piece of such corrugated metal over the freshly cast final section and apply vibration to its outer surface to impress on the final section the corrugations which have been formed in the remaining portion of the kiln lining.

After the last section of refractory castable has set, rings 10 and forms 21 can be removed from the kiln. It will be appreciated that the adjustable attachment between segments 11 making up rings 10 will be of assistance in removing rings 10 from the kiln since segments 11 can be adjusted to form a ring of smaller circumference or even used to disassemble rings 10 within the kiln. It will also be apparent that rings 10 and spacer bolts 17, as Well as forms 21, can be reused in subsequent kiln lining jobs.

An advantage of the apparatus of this invention is that spacer bolts 17 and adjustable joining elements 12 together permit adjustment of rings 10 to any size of kiln, and to minor irregularities within a kiln, as well as to any desired thickness of kiln lining.

It will be apparent that the apparatus of this invention can be also be used for casting a lining in a circular kiln whose longitudinal axis is vertical, for example a shaft kiln.

What is claimed is:

1. Method of forming a monolithic cast refractory lining in a rotary kiln having a metal shell, said method comprising:

(a) inserting in said kiln a plurality of segmented rings, said rings being longitudinally spaced along the length of the kiln and each ring being substantially concentrically located within the kiln shell by means of at least three circumferentially spaced spacer elements removably attached to said rings, the outer surfaces of each of said rings being substantially the same distance from the kiln shell, the spacer elements on each ring being substantially aligned in a longitudinal direction along the kiln, thereby forming a longitudinal set of spacer elements;

(b) placing a starter board in a lower quadrant of the kiln, said starter board extending radially from the kiln shell to the outer surface of the rings and longitudinally the length of the section of kiln to be lined with castable refractory;

(c) attaching forms to the outer surfaces of the rings, said forms extending longitudinally the length of the kiln section to be lined and circumferentially from the starter board for a distance not greater than the circumferential distance to the adjacent longitudinal set of spacer elements;

(d) placing castable refractory in the casting space formed by the starter board, the kiln shell, and the forms;

(e) removing the support elements circumferentially adjacent the open side of the casting space whenever necessary to clear the outer surface of the rings for placement of additional forms;

(f) attaching additional forms to the outer surfaces of the rings to continuously circumferentially extend the forms a distance not greater than the distance to the next circumferentially adjacent longitudinal set of spacer elements;

(g) repeating steps (d), (e) and (f) to cast further sections of kiln lining, at intervals turning the kiln, after the cast refractory has taken an initial set, so

that the space being filled with castable refractory lies in a lower quadrant of the kiln, until the last longitudinal set of spacer elements has been removed;

(h) removing the starter board; and

(i) casting the final section of lining with the kiln turned so that the refractory castable is placed in the final section at the circumferentially lowest portion of the kiln.

2. Method according to claim 1 wherein said forms are corrugated metal sheet.

3. Method according to claim 1 wherein metal anchors are welded to the kiln shell and embedded in the refractory castable.

4. Method according to claim 1 wherein vibration is applied to the refractory castable immediately after it is placed.

5. Method according to claim 1 wherein said forms are wood.

References Cited UNITED STATES PATENTS 3,672,649 6/1972 Allen 26430 X 3,492,383 l/ 1970 Heimgartner 26430 1,734,773 11/1929 Murray 249-11 X 875,518 12/1907 Georgenson 249-184 X ROBERT F. WHITE, Primary Examiner T. P. PAVELKO, Assistant Examiner 

